1. Field of the Invention
The present invention relates to integrated semiconductor laser and laser amplifiers and, more particularly, to a method and apparatus for controlling the direction and focus of a laser beam by applying electric signals to an integrated semiconductor laser and laser amplifier.
2. Description of Prior Art
One of the oldest methods of directing and focusing lasers uses mechanical systems with a moving mirror or a moving lens i order to change the direction and focusing of a laser beam. The disadvantages of these systems are that they are very slow and very cumbersome. In recent years, various methods have been developed to deflect laser beams. The laser beam deflection methods include: use of a KDP crystal, use of the photoelastic effect, and by Bragg diffraction using acoustic waves. While these methods are much faster than mechanical deflection, they cannot be embodied into an integrated semiconductor laser device.
Development in the field of non-linear optics has also played a role in controlling the direction of a laser beam. Within the field of non-linear optics, a phase conjugate mirror has been developed. Using the phase conjugate mirror, the phase angle of a reflected wave can be made to conjugate that of the incoming wave. The reflected wave then retraces the path of the incident wave with a conjugated phase angle. Using this type of device, a laser with controllable beam direction can be developed. However, conjugate mirrors cannot be embodied into an integrated semiconductor laser device.
Each of the above laser direction and focusing control devices requires a complex optical system involving many precisely located components. To date, it has not been possible to direct and focus lasers using a simple single integrated semiconductor laser device. The present invention seeks to overcome the complexity of laser beam directing and focusing devices as well as provide a direction and focusing control which will operate much faster than the previously developed systems.